High pressure liquid chromatography (HPLC) is a new technology now being developed for separation, partial purification and quantification of peptides. Work in this lab has focussed on achieving optimal high resolution separations of opiate peptides from other closely related compounds of biological origin. Results have shown that retention of peptides containing up to 20 amino acids on reverse phase HPLC columns can be predicted on the basis of amino acid composition, and the chromatographic conditions of pH and solvent composition can be decided on the basis of simple calculations. The results will be of use in any study which requires isolation of peptides for purpose of identification, or proof of purity and accuracy of measurement.